以類別索引表為基礎之彩色浮水印技術研究

A Study of CIT-based Color Image Watermarking Method

劉蕙芩(Hui-Qin Liu)

指導教授 ： 陳建彰

淡江大學/工學院/資訊工程學系資訊網路與多媒體碩士班/碩士(2019年)

https://doi.org/10.6846/TKU.2019.00954

摘要

浮水印技術為嵌入資訊於數位影像中之一種技術，再藉由資料抽取的步驟，取出原嵌入的資訊。而可逆浮水印技術(Reversible Image Watermarking)在抽取已嵌入的浮水印資訊後，可以同時獲得完整的原始影像。可逆浮水印技術對於著作權的保護，有很重要的保護功能。
至目前有眾多可逆浮水印的技術被提出。近年來，有學者提出類別索引表(Class Index Table, CIT)方法，藉由區塊內排列順序的調整，建立視覺上與掩護影像相似的浮水印嵌入後的圖。然而，直接使用類別索引表的浮水印嵌入後之視覺效果並不好，本論文研究使用彩色影像間之配對方式，透過影像區塊距離矩陣、貪婪式配對方式及類別索引表嵌入三大步驟，進行快速的計算處理，以期能獲得高效能及高品質之掩護影像。本論文比較多種類別索引表的方法，並期能獲得較佳的參數組合。

關鍵字

可逆浮水印技術 ； 類別索引表 ； 距離配對

並列摘要

A reversible image watermarking scheme recovers the original image after extracting the embedded watermarks. A conventional CIT-based image watermarking method segments digital images to combination of non-overlapped blocks. Blocks of the original image is one-to-one mapped to blocks of the covered image for acquiring the watermarked image. The mapping table is needed for perfectly recovering the original image from the watermarked image. Quality of the watermarked image is determined by mapping procedure and the selection of mapping table. In this study, we examine different selection strategies to present an efficient method for acquiring good quality of the watermarked image. Analysis with other selected strategies, like random preprocessing or nearest matching, are compared. Moreover, color image has better watermarked image quality than gray-level image. For acquiring good watermarked image, nearest matching is the so-far best strategy on the CIT-based method. Experimental results show that the watermarked image has a similar visual effect to the target image but can perfect recover to the original image by using the mapping table.

並列關鍵字

Class Index Table (CIT) ； random preprocessing ； nearest matching

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